Fiber optic technology is based on the transmission of data using optical or light signals along a small optical fiber. This technology is currently being used in a variety of computer and communications applications due to the increased bandwidth allowing higher data rates through optical fibers as compared to traditional copper wire transmission methods. However, since computers and communications devices still operate using electrical signals, the optical signals received via the optical fibers must be translated to electrical signals, and the electrical signals transmitted by the devices must be translated to optical signals for communication over the optical fibers. This function is typically performed by various photo detectors, transceivers and optical/electrical converters, these optical devices being included within photonic integrated chips to which the optical fibers are coupled.
For effective signal conversion, the optical fibers must be precisely aligned with appropriate devices, such as photo detectors, within the photonic integrated chips for translation of the optical signal. Failure to precisely align the optical fiber with the photo detectors will result in optical loss and consequent loss of portions of the communicated optical signal. As an optical fiber is brought into alignment with the photo detector (or other device) it has unrestricted movement in all six degrees of freedom, the six degrees of freedom being lateral movement in the x and y directions, forward/backward movement in the z direction, rotation along the z axis, tilt along the x axis and tilt along the y axis. Because of the amount of unrestricted motion, it is extremely difficult to align the optical fibers with the photo detectors. The fact that the optical fibers are extremely small and the alignment must be precise for effective transfer adds to this complexity. In fact, the task is so complex and the necessity of precise alignment is so critical, in many cases the task cannot be performed by automated means but instead must be performed manually by skilled technicians. The only alternative is to install complicated alignment means within the system to aid alignment, adding significant expense. Also, because alignment of the additional devices needs to be as precise as alignment of the optical fibers, many of these adjustment devices still result in misalignment of optical fibers due to misalignment of the adjustment devices.
U.S. Pat. No. 5,499,311, entitled “RECEPTACLE FOR CONNECTING PARALLEL FIBER OPTIC CABLES TO A MULTI-CHIP MODULE,” discloses a connector and receptacle for connecting optical fibers to a multi-chip module. The receptacle is a plastic body having holes for receiving the optical fibers. The body is surrounded by a jacket having a thermal expansion joint. The recess also has alignment holes at the bottom for receiving metal pins located on the connector that also holds the optical fibers. As the connector holding the optical fibers is brought into contact with the receptacle, the metal pins are inserted into the alignment holes aligning the optical fibers with the holes for receiving the optical fibers. The present invention does not align optical fibers in this manner. U.S. Pat. No. 5,499,311 is hereby incorporated by reference into the specification of the present invention.
U.S. Pat. No. 6,137,929, entitled “SYSTEM AND METHOD FOR INTERFACING OPTICAL FIBERS WITH OPTICAL COMMUNICATIONS DEVICE VIA AN OPTICAL FIBER FACEPLATE,” discloses a connector for transmitting optical signals to an optical fiber communications device. The connector has optical fibers of larger diameter than the optical fibers to which it is connected. This obviates the need for precise alignment of either the fibers or the connector. The present invention does not rely on enlarged connecting fibers for alignment, and thus does not use the method of this invention. U.S. Pat. No. 6,137,929 is hereby incorporated by reference into the specification of the present invention.
U.S. Pat. No. 6,250,820, entitled “ELECTROOPTICAL COUPLING COMPONENT,” discloses a system that couples two electrooptical components by mating indentations and protrusions on the two components. Specifically, a first substrate having optical waveguides has a trapezoidal indentation. A second substrate having optical fibers further includes a trapezoidal protrusion and recesses for the waveguides. The first substrate can be slidingly mated with the second substrate such that the trapezoidal indentation and protrusion interlock, thereby aligning the waveguides and recesses. This method of alignment is not used in the present invention. U.S. Pat. No. 6,250,820 is hereby incorporated by reference into the specification of the present invention.
As can be seen from the prior art, to align optical fibers with waveguides, photo detectors or other suitable devices it is generally necessary to precisely align other components as well. Though other alternatives may exist, these can result in optical losses from other areas and are not suitable for applications that have strict space limitations. It is therefore desirable in the art to have an alignment architecture providing a low optical loss that can be aligned using a simple optical means.